where P is the total power of the transmitters, [P.sub.x] and [P.sub.y] are the real and the imaginary parts of the 4-QAM
Caption: Figure 3: Illustration of unconditional and conditional 4-QAM
For N = 128 subcarriers, 4-QAM
symbols are generated by loading 72 bits into the system.
The computational complexity comparisons of the improved QRD-M algorithm, original QRD-M algorithm, OB-MMSE algorithm, SD algorithm, and the ML algorithm are provided in Figure 4 over 4x4 MIMO channel with [N.sub.A] = 3 for 4-QAM
For the first consideration (as presented in the first set of plots), SU demands in queue 1 are served at a data rate of 6 bits per symbol (64-QAM modulation) for each unit of time, while demands in queue 2 are served at a rate of 2 bits per symbol (4-QAM
modulation) for each unit of time.
and 16-QAM, MDV is 16, but for 8-QAM the MVD is 6.18.
Los investigadores observan como, para decisiones basadas en distancia minima Euclidiana, el esquema propuesto supera el desempeno frente al ruido de la modulacion por amplitud en cuadratura de cuatro estados (4-QAM
), lo que les permite afirmar que un adecuado diseno de la constelacion en un espacio de mas de dos dimensiones permite reducir la tasa de error de bit sin comprometer significativamente la eficiencia espectral.
In case of 4-QAM
the values [X.sup.c.sub.k] originating from the constellation point marked by gray color may fall in the following regions:
The average BER, derived using 4-QAM
modulation format, is equal 
The CM criterion can successfully equalize signals characterized by source alphabets not possessing a constant modulus (e.g., 16-QAM), as well as those possessing a constant modulus (e.g., 4-QAM
) (see Fig.
Also shown is the curve corresponding to the 4-QAM
scheme (which coincides with the curve of the 2-PAM and 2-PSK schemes).
The analytical results for Q-PSK or 4-QAM
under Nakagami-m fading channel including the Rayleigh fading channel.